Electronic mail, or e-mail, stores messages and delivers them when the addressee is ready to receive them, in a so-called "store-and-forward" manner. The basic e-mail system consists of a front-end mail client and a back-end mail server. The e-mail client is a program running on an individual user's computer which composes, sends, reads, and typically stores e-mail. The e-mail server is a program running on a network server which the e-mail client contacts to send and receive messages. For example, INTERNET e-mail utilizes a SMTP (Simple Mail Transport Protocol) mail server to send mail and a POP (Post Office Protocol) server to receive mail. To send e-mail, an e-mail client contacts an SMTP mail server which moves the message to a POP server where it is sorted and made available to the recipient. The recipient's e-mail client logs on to the POP server and requests to see the messages that have accumulated in the mailbox. Conventionally, e-mail communications involve the transfer of text. Text-only e-mail, however, does not utilize the full potential of this emerging form of communications.